A Totally SDR Single-Frequency Augmentation Infrastructure for RTK Land Surveying: Development and Test

Nowadays, high accuracy services for Land Surveying are limited by the need of costly Reference Stations infrastructures and rover receivers.
SDR technology is rapidly developing and allows several advantages in terms of costs and flexibility. This paper, moves from an implementation of a GNSS single-frequency SDR receiver, code and phase, able to process code and phase and to perform RTK. It is totally based on COTS and runs on Notebooks and Tablet. It describes the development of an augmentation infrastructure (Reference Stations and rover receivers) totally based on SDR technology.
An extensive test campaign has been carried out in Italy involving Professional Land Surveyors and Institutional actors (e.g. the Italian Land Agency, a branch of the Italian Revenue Agency), for evaluating the new solution for real Land Registry (named “Cadastre” in Italy) update through GNSS RTK surveying.
Traditional topographic instruments and GNSS have been used for demonstrating the suitability of the proposed solution for the institutional Land Surveying sector. A performance analysis has been carried in order to identify the weakness and strength of such solution for future development. The impact of baseline lengths and number of visible satellites has been analyzed, as well as communication network impacts, feeding in parallel the SDR receiver and the Hardware one to the same antenna through an antenna splitter.
The analysis demonstrated that the convergence time and the expected performances in terms of correct fixes and achievable accuracy are in line with hardware GNSS single frequency receivers. Major factors impacting on the convergence time and correct fixes percentage are the baseline length, the number of visible satellites and the presence of multipath. Communication losses between the Network Control Centre and the rover have also a relevant impact on performances. The achieved results are very promising for a full implementation of the system.

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Proceedings of the 29th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2016)
September 12 - 16, 2016
Oregon Convention Center Portland, Oregon